The present invention relates to a ball spline bearing for use in bearing a load which moves in the axial direction and/or in the rotational direction.
As shown in FIGS. 14 and 15 showing a prior art, a typical conventional ball spline bearing has an outer sleeve 100, a spline shaft 101 and a ball retainer 102 interposed between the outer sleeve 100 and the spline shaft 101. The ball retainer 102 has a plurality of axial slits 103 receiving a multiplicity of torque-transmitting loaded balls 104 adapted to roll along these slits 103. In this conventional ball spline bearing, the ang1e .theta. at which each ball 104 contacts the loaded ball grooves 105 and 106 in the outer sleeve 100 and the spline shaft 101, i.e. the angle formed between a line X--X interconnecting the center O of the outer sleeve 100 and the center O' of the ball 104 and a line Y--Y interconnecting the points p.sub.1 and p.sub.2 of contact of the ball 104 with the loaded ball grooves 105 and 106, is about 30.degree., so that the load bearing capacity or torque transmitting capacity of the ball spline bearing is limited undesirably. In addition, the necessity of the ball retainer 102 disposed between the outer sleeve 100 and the spline shaft 101 inconveniently increases the number of parts to raise the cost of production of the ball spline bearing and to complicate the process of assembling unfavourably.